DE2800732A1 - BEARING ARRANGEMENT FOR A ROTARY LISTON MACHINE - Google Patents

Description

Dr. F. Zumstein s ^ n. - Dr. F =. Afsm? Nn - Dr. R. Koenigsberger Dipl.-Phys. R. Holzbauer - D; pl. Ing.: ⁼ . KKngseisen - Dr. F. Zumstein jun.

PATENT LAWYERS 280073? Munich 2 ■ Bräuhausstraße 4 - Telephone collection no. 225341 Telegrams Zumpat - Telex 529979

S 1674 40 / m ■ Te / Li

SÜLLAIR CORPORATION, Michigan City. Indiana, USA

Bearing arrangement for a rotating basket machine

The invention relates to a bearing arrangement for a rotary piston machine with lubricant / coolant injection. An abnormal screw machine includes a housing with two axial, intersecting bores, a low pressure connection at one end and a high pressure port at the other end. The two rotors with complementary each other Cutting screws are rotatably arranged in the bores and are used in the end walls of the housing built-in bearings. Usually the bearings of a rotary screw machine are the first components which fail during normal operation. The bearing size is limited by the center-to-center distance of the rotors and can not be enlarged to provide a heavier bearing

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the. Accordingly, it is desirable that the thrust loads are distributed to a high-performance bearing provided at the high pressure end, that has the appropriate bearing properties selected with a view to maximum bearing life.

The most common rotary screw gas machine is the gas compressor, which is widely used to compress air and coolants. Most of the following explanation relates to the machine working as a gas or air compressor. However, the novel bearing arrangement can also be used in others Rotary piston machines with a pressure differential between the inlet and the outlet can be used.

The radial bearing load on the depressing? the machine is proportionate small because the fluid between the rotors is at a low pressure. In the case of an air compressor the pressure at the inlet is atmospheric pressure. In contrast, at the high pressure end is the one enclosed between the rotors Fluid under high pressure and there is significant radial loading on the bearings at the high pressure end. That High pressure fluid at the high pressure end is also rare between the end faces of the rotors and the end wall of the housing. This creates a significant axial force on the rotors. ^ It is desirable that the rotors are so axial in the housing are attached that the end faces a substantially fixed game against the end wall at the high pressure end of the Have housing. There is a variable play, such as that to absorb the thermal expansion of the rotors, at the low-pressure end of the housing provided. This relationship requires that the bearings be at the high pressure end in addition to a high radial load take a high thrust load.

Earlier rotary screw machines used double ball bearings at the high pressure end. In such ball bearings, the balls double angular contact with each race and fix the rotors axially in the housing. These bearings are quite expensive.

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Recently, in US Pat. No. 3,388,854, it was suggested that each rotor be fitted with a combination of roller and ball bearings each end is stored. The main thrust bearing is provided at the high pressure end. Springs between the bearings for each rotor at the low pressure end, the rotors are axially fixed and prevent them from hitting the outlet end of the housing. One on the

outer race of the ball bearing for one rotor on the down-acting Pistons

Printing y distributes the thrust load between the bearings at each one End. In U.S. Patent 3,947,078 there is one. Bearing arrangement specified, the thrust loads between single tapered roller bearings at each end of the machine.

A main object of the invention is to provide a Rotary piston machine with a bearing arrangement that allows easy adjustment of its components.

According to the invention, a screw compressor has a bearing for high axial and radial loads between each rotor shaft and the housing at the high pressure end and a radial bearing between each rotor shaft and the housing at the low pressure end. One such a bearing arrangement results in a floating rotor arrangement which is movable in the direction of the thrust load which is causing is determined by a pressure differential of the working fluid at the bearing at the high pressure end using a radial load to generate an axial force opposing the thrust load.

In detail, the high-performance bearing is for thrust and radial Load at the high pressure end a tapered roller bearing. The radial bearing at the low pressure end is a cylindrical roller bearing with separable inner or outer race.

A feature of the invention is that the compression of the working fluid resulting axial force an axial force on an outer bearing cap of the bearing

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Exerts high pressure end via a cone, creating an accurate radial definition of the rotors when the machine is running is in operation.

Another feature of the invention is the use of either lock nuts or a holder with washers, so that the rotor end play and the inner bearing clearances can be adjusted at the same time.

Because of the simplicity of construction using a single tapered roller bearing at the outlet end, the cost is lower than with a double shoulder ball bearing or a cylindrical roller bearing and a shoulder ball bearing.

The invention is explained in more detail with reference to the drawing, for example. It shows:

1 shows a schematic view of a screw compressor with a cooling system;

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1; 3 shows an enlarged longitudinal section through the compressor with the central part omitted.

A normal screw compressor is shown schematically in FIGS. A housing 10 has axial, intersecting Bores 11 and 12 which receive a penetrating rotor 13 and a receiving rotor 14, respectively. Helical Elevations and grooves on rotors 13 and 14 come into engagement, when the rotor turns. Gas is drawn into an inlet port 16, enclosed in the housing, compressed when let protrusions and grooves engage, and at the outlet port 17 launched. In an expansion machine, the high pressure gas supplied to the outlet port 17 drives the rotors and becomes released after the expansion at the inlet port 16 ..

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The temperature of the compressor is controlled by the introduction of a suitable refrigerant, such as mineral oil, which also serves to lubricate the rotors and provides a seal between the rotors and between each rotor and the housing. The pressurized gas from the outlet port 17 is supplied to an oil separator 19. Substantially oil-free, compressed gas is dispensed via line 20, the oil being recirculated under pressure from the compressed gas via line 22 through heat exchanger 21 to the compressor and via line 23 to the inlet bearings, which will be described in detail. Alternatively, the oil can drain from the separator 19 to a sump 24 and be recirculated by a pump 24 'at a controlled pressure, independent of the pressure of the compressed gas and above this pressure if necessary.

3, the housing 10 includes a generally cylindrical body 25 with inlet and outlet end plates 26 and 27 and inlet and outlet covers 28 and 29. The rotors 13 and 14 have shafts extending from each end and are journalled in bearings carried by the end plates 26 and 27.

The rotors 13 and 14 have at the inlet end shafts 32 and 33 which are mounted in cylindrical roller bearings 34 and 35, which in turn through the inlet end plate 26 extending bores 36 and 37 are received. The bearings 34 and 35 are Axially floating arranged, the cylindrical roller bearings have a separable race and are particularly useful a radial load. Since the bearings for the two shafts are similar, only bearing 34 is used for the penetrating Rotor 13 is described in detail. The bearing 34 has an inner race 40 that is mounted on the shaft 32 and abuts a shoulder 41 thereof while an outer race 32 is received in the bore 36 of the inlet end plate 26 will. Cylindrical rollers 43 are in a cage 44

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between the inner race 40 and the outer race 42 held. The bearings 34 and 35 are preferably lubricated by introducing cooled oil through the inlet cap 28.

The rotor shafts 52 and 53 are each in tapered roller bearings at the outlet end 54 and 55, which in turn are received in bores 64 and 65 arranged in the outlet end plate 27 will. Located at the outlet end between rotors 13 and 14 Compressed gas exerts a radial force on rotors 13 and 14 which tends to separate the rotors to press. Accordingly, the bearings 54 and 55 must withstand a greater radial load than the inlet bearings 34 and 35. The rotors 13 and 14 are moved by a considerable axial force from the compressed gas to the inlet end pressed. This gas is located between the inner end surface of the outlet end plate 27 and the end face of the rotors 13 and 14, where a running game indicated by arrows at 57 is provided.

The construction of the exhaust end bearings is best seen in FIG. Since the bearings for the two rotors 13 and 14 are similar, only the bearing 54 of the penetrating roitor 13 will be described in detail. The bearing 54 has an inner Race 60, which rests on a load ring 78, which in turn on a shoulder located on the shaft 52 61 is present. An outer race 68 is held in bore 65 by tapered rollers 66 on a shoulder. These tapered rollers are held in the operating position between the inner race 60 and the outer race 68 by a cage 67. The inner race is held on the load ring 78 by one or more lock nuts screwed onto the shaft 72 or a retainer 75 with washers 76 (rotor 14) located axially outside the inner race, and the like

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press inward on its outer end. The holder 75 can by not shown screws or the like. On the shaft 53 be attached. The load ring 78 provides a spring force that urges the inner race 60 against the lock nut 72 presses. The axial positions of the outer race 68 and the inner race 60 form the end play 57 between the inner The end face of the outlet end plate 27 and the end face of the rotors 13 and 14. The distance can be selected by providing a suitable washer 76 between the holder and the rotor or by adjusting the lock nuts, which effectively changes the axial position of the inner race on its respective shaft. The lubrication the bearings 54 and 55 are preferably carried out by guiding of cooled oil through outlet end plate 27 onto the bearings.

The pressure differential created by the working fluid at each end of the rotors 13 and 14 forms a minimum axial one Force directed towards the low pressure end and the outer race in each bearing 54 and 55 against the inner race 60 centered in the absence of other axial or compensating forces.

The radial load on rotors 13 and 14 at the outlet end is divided by the tapered roller bearings 54 and 55 into a radial component and an axial component. The axial component opposes the axial gas load and thereby reduces the resulting rotor thrust load on the exhaust bearings 54 and 55. The angle of the outer race 68 becomes like this chosen so that the thrust resulting from the radial load is always smaller than the pressure thrust load on the corresponding rotor is held in order to maintain the correct centering of the rotors 13 and 14 and the clearance between the rotors 13 and 14 and the outlet end plate 27 to adjust.

The angle of the tapered surface of the outer race 68 relative to the bearing axis is a factor in determining the thrust

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last that takes up the camp. Increasing this angle increases the ratio of axial to radial for the bearing Operating value.

At a standstill, when there are no gas forces, the tapered roller bearings 54 and 55 bear the weight of the rotors 13 and 14. The radial load from the weight creates a resultant thrust force in the bearings that tends to support the rotors 13 and 14 against the outlet end plate 27 to pull. This resulting thrust is absorbed and supported by the surface on the end face of the rotors 13 and 14 and the Inside of the outlet end plate 27. That is, the surface material the rotors and the end plate must be chosen so that a combination of materials is provided, the bearing properties owns. The surface quality can have the same properties as in hydrodynamic bearings.

In the case of the bearing arrangement according to the invention, there is no axial Bearing adjustment or a bearing preload on the radial bearing at the low pressure end to maintain suitable clearance provided at the bearing at the high pressure end. To achieve a simplified structure and a longer service life of the Bearing, the bearing play is provided at the same time during the setting of the rotor end play.

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Claims (15)

Patents s ρ back e Bearing arrangement for mounting the rotor shafts in the housing of a rotary piston machine, with a housing with a Low pressure port at one end and a high pressure port at the other end and with main and secondary rotors Shafts on which the rotors are mounted for rotation in the housing, the rotors intermeshing helically Have bumps and grooves that trap gas as they move the gas between the openings, and with the rotors at the low pressure end of a low radial load, at the high pressure end of a high radial load Are subject to load and axial load pushing the rotors towards the low pressure end, characterized by an axially floating radial bearing between the rotor shaft and the housing at the low-pressure end, that of the rotor shaft allows axial movement with respect to the housing, and through a combination of radial and axial bearings between the rotor shaft and the housing at the high pressure end, the combined bearing being part of the radial The load is converted into an axial force that opposes the axial load induced by gas pressure is, so that the axial load introduced by gas pressure is at least partially compensated. 2. Bearing arrangement according to claim 1, characterized in that that every combination bearing is a tapered roller bearing. 3. Bearing arrangement according to claim 1, characterized in that each combination bearing 809833 / 0-7 23 ORIGINAL! NSPECTED has a raceway through an inner race on the rotor shaft and an outer race in the housing is formed, with rollers between the inner race and the outer race and means for locking the position of the outer race so that the rotor can be positioned with respect to the housing. 4. Bearing arrangement according to claim 3 * characterized in that each combination bearing a Tapered roller bearing is. 5. Bearing arrangement according to claim 3> characterized in that that the rotary piston engine is a compressor, and that the combination bearing axial load exerted depends on the discharge pressure of the compressor. 6. Bearing arrangement according to claim 3> marked "-net by a locking nut engaged with a rotor shaft for positioning one of the races with respect to the rotor and to establish the position of the rotor in the housing. 7. Bearing arrangement according to claim 3, characterized by a washer and a holder, which engages a rotor shaft for positioning and manufacturing one of the races with respect to the rotor the position of the rotor in the housing. 8. Bearing arrangement according to claim 1, characterized in that that the radial bearing at the low pressure end is a cylindrical roller bearing with a detachable race is. 9. Bearing arrangement according to claim 1, characterized in that g e - 809833/0723 yc- 3 draws that the radial bearing opposite one the housing fixed outer race and a movable inner race attached to the rotor shaft having, wherein the radial bearing allows thermal expansion of the rotors. 10. Bearing arrangement for supporting each rotor shaft in the housing of a rotary screw gas machine / with a housing a low pressure port at one end and a high pressure port at the other end, and with main and secondary rotors with shafts on which the rotors are mounted for rotation in the housing, the rotors intermeshing have helical ridges and grooves that trap gas as they move the gas between the openings move, and with the rotors at the low pressure end a low radial load, at the high pressure end a high radial load and axial load are subjected to the rotors to the low pressure end pushes towards, characterized by a radial bearing between the rotor shaft and the housing at the low pressure end, and by an axially locking bearing with high load capacity for radial load and axial Thrust between the rotor shaft and the housing at the high pressure end. 11. Bearing arrangement according to claim 10, characterized in that the radial bearing is axial is arranged floating to a thermal expansion and axial movement of the rotor shaft to the low pressure end of the To enable housing, wherein the axially locking bearing has a raceway with an inwardly directed cone, which radially centers the rotor shaft when the rotor is subjected to an axial load that the Rotor shaft moved to the low pressure end. 80983370723 writ 12. Bearing arrangement for supporting each rotor shaft in the housing of a rotary screw gas machine, with a housing a low pressure port at one end and a high pressure port at the other end, and with main and secondary rotors with shafts on which the rotors are mounted for rotation in the housing, the rotors meshing with each other, to move the gas between the openings, and with the rotors at the low pressure end of a low one radial load, subject to high radial load and axial load at the high pressure end, which pushes the rotors towards the low pressure end, characterized by an axially floating one Bearings with radial load capacity between the rotor shaft and the housing at the low pressure end of the Rotor shaft, which enables the rotor shaft to move axially with respect to the housing, by means of a bearing axial load capacity between the rotor shaft and the housing at the high pressure end of the rotor shaft with a first race carried by the housing, which is fixed against axial movement inward towards the low-pressure end is, with a second race, which is movable from the rotor shaft axially outward relative to the first race is carried, and with rollers between the races, and by means for axially positioning the second raceway on the rotor shaft with a locking member, which is adjustably attached to the rotor shaft, axially outward with respect to the first race, which is supported inwardly on the outer end of the first race, around the first race against axial movement outward on the rotor shaft, causing the operation of the gas engine to keep the rotor to the low pressure end moves the housing, wherein the locking member moves the second raceway toward the first raceway, until the thrust bearing is in effective engagement. ^ 809833/0723 13. Bearing arrangement according to claim 12, characterized in that the locking member is a locking nut which is axially outside of the second race is screwed onto the rotor shaft. 14. Bearing arrangement according to claim 12, characterized in that the locking member is a holder which is attached to the end of the rotor shaft and extends radially outward therefrom and abuts the outer end of the second race, and by means for positioning a washer between the rotor shaft and the holder for modification the axial position of the holder in relation to the rotor shaft. 15. Bearing arrangement according to claim 12, characterized in that axially inward of the " second raceway on the rotor shaft a shoulder is formed, and characterized by an intermediate the shoulder and the second race arranged load ring to provide a spring force that the second The raceway presses against the locking member radially outward. 809833/0723